1. Field of the Invention
The present invention relates to an image signal recording apparatus for recording an image signal on a recording medium.
2. Description of the Related Art
Electronic still video cameras have heretofore been known as recording/reproducing apparatus for recording a video signal obtained through image sensing means such as a video camera on a recording medium such as a magnetic disc and for reproducing the video signal recorded on the recording medium.
Currently known types of electronic still video cameras, however, can only record or reproduce a television signal which, at best, conforms to current television systems (for example, the NTSC system). Accordingly, in the case of a format which complies with the NTSC system, the number of scanning lines is 525 lines per frame with a horizontal resolution of 350 TV lines.
In such a situation, with the present improvement in the quality of images handled by video tape recorders, it has been strongly desired to improve the quality of images processed by electonic still video cameras.
However, the degree of resolution adopted by the current electronic still video cameras is not sufficient to effect recording and reproduction of still images of satisfactory quality. Moreover, even if a video signal reproduced from a magnetic disc is printed in the form of a still image, the resultant image is an image whose quality is far lower than the quality of an image obtained by a conventional camera such as a silver-halide type camera.
A novel television system of increased quality such as a high-definition television system has recently been proposed, and various experiments on such a novel television system have been conducted. When electronic still video cameras which comply with the new television system are to be designed, designers will encounter the problem that it is very difficult to realize satisfactory recording and reproduction using the current format. Moreover, if a new format is adopted in accordance with the new television system, it will be difficult to maintain compatibility with the conventional format.
Moreover, since the band of a chrominance signal is narrower than the band of a luminance signal, the aliasing of a signal tends to easily occur in the band of the chrominance signal, particularly when imaging is effected by means of a solid-state image sensor. The result is that the quality of an image is deteriorated due to the occurrence of the aliasing.